High-density interconnect (HDI) structures have received a great deal of attention, as a result of their advantages in fabrication of complex systems. In general, HDI structures allow the interconnection of relatively large numbers of integrated-circuit chips into complex systems in a cost-effective manner. More particularly, integrated-circuit chips are mounted on heat-conductive or heat-sinking substrates, with their interconnection electrodes or pads lying in a common plane. One or more layers of dielectric film material, patterned with interconnection conductors, are placed over the chips to be interconnected, and connection vias are defined through the dielectric layers to interconnect the chips with the electrically conductive interconnection pattern on the film.
Various aspects of HDI structures and fabrication are defined in U.S. Pat. No. 5,338,975, entitled High Density Interconnect Structure Including A Spacer Structure And A GAP, issued Aug. 16, 1994 in the name of Cole et al., and in U.S. Pat. Nos. 5,561,085 and 5,757,072, entitled Structures for Protecting Air Bridges On Semiconductor Chips From Damage, issued May 26, 1998 in the name of Gorowitz et al. More particularly, these patents describe arrangements for protecting sensitive portions of semiconductor chips from damage due to the presence of interconnection film in HDI structures. Such sensitive portions of semiconductor chips may include airbridge structures, which are liable to be crushed, and transmission-line or resonant structures, the properties of which may be affected by proximity to dielectric materials. These prior techniques for generating protective regions for protecting sensitive regions of the semiconductor chips are effective, but may be too complex for use under some conditions, or too expensive. In particular, some protective techniques required the individual placement of protective caps over sensitive portions of each of the chips before the application of the HDI interconnect layers.
Improved methods for making HDI-connected structures are desired.